In a display device such as a liquid crystal display device, a storage capacitor is configured to maintain a voltage of a pixel electrode in a certain range for a preset time, after a thin film transistor is turned off. The storage capacitor is required to have a sufficient capacitance to avoid problems like pixel flickering, low contrast, and cross-talk, and to improve the display quality. Increase in an area of the storage capacitor may increase the capacitance. Since the storage capacitor is generally formed of an opaque metal, when the area of the storage capacitor is increased, an aperture ratio of a pixel unit reduces and the display luminance reduces.